Bicellum brasieri, a freshwater protist that lived nearly one billion years ago, had two distinct cell types and could be the earliest multicellular animal ever recorded. Found in the Scottish Highlands, the microfossil reveals a new insight into the transition of single-celled holozoans into more complex multicellular animals. Bicellum brasieri in mature form; all specimens were preserved in petrographic thin sections from the Diabaig Formation stratotype,...
